It is due to the false confidence that they have the super fast trading machine therefore can sell in front of other bag holders in case the sell-off starts.
And that's a perfect setup for a quick sell-off. The exchange will be jamed and no one can get out. An ordered dump will be put into place and you have quite a few trading house blow-up.
That's what will happen this year. If you don't see it coming, you are in denial.